Truncus Arteriosus

Heart With Truncus Arteriosus

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Normally, the aorta originates from the left ventricle and the pulmonary artery originates from the right ventricle. In the case of truncus arteriosus, the aorta and pulmonary artery are not fully separated, resulting in a single arterial trunk that arises above a VSD. The low-oxygen blood from the right ventricle and the oxygen-rich blood of the left ventricle mix and are pumped to both the lungs and the body. As a result, the lung circulation is exposed to high pressure and increased blood flow.

Corrective surgery must be performed in the first six months of life. Complete repair requires closure of the VSD and separation of the great arteries. The VSD is closed with a patch such that the truncus originates in the left atrium. Next, a connection is made between the branch pulmonary arteries and the right atrium using a valved conduit (tube containing a valve). Any connections between the branch pulmonary arteries and the truncal vessel are also patched closed.

What Is Normal Cardiac Anatomy?

When your child has a congenital heart defect, there's usually something wrong with the structure of his or her heart's structure.

Heart With Normal Cardiac Anatomy

When your child has a congenital heart defect, there's usually something wrong with the structure of his or her heart's structure.

The heart is composed of four chambers. The two upper chambers, known as atria, collect blood as it flows back to the heart. The two lower chambers, known as ventricles, pump blood with each heartbeat to the two main arteries (the pulmonary artery and the aorta). The septum is the wall that divides the heart into right and left sides. The atrial septum separates the right and left atria; likewise, the ventricular septum separates the two ventricles.

There are four valves that control the flow of blood through the heart. These flap-like structures allow blood to flow in only one direction. The tricuspid and mitral valves, also known as the atrioventricular valves, separate the upper and lower chambers of the heart. The aortic and pulmonary valves, also known as the arterial valves, separate the ventricles from the main arteries. Oxygen-depleted blood returns from the body and drains into the right atrium via the superior and inferior vena cavas. The blood in the right atrium then passes through the tricuspid valve and enters the right ventricle.

Next, the blood passes through the pulmonary valve, enters the pulmonary artery, and travels to the lungs where it is replenished with oxygen. The oxygen-rich blood returns to the heart via the pulmonary veins, draining into the left atrium. The blood in the left atrium passes through the bicuspid, or mitral, valve and enters the left ventricle.

Finally, the oxygen-rich blood flows through the aortic valve into the aorta and out to the rest of the body.

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A to Z: Hypoplastic Left Heart Syndrome

A to Z: Hypoplastic Left Heart Syndrome

May also be called: HLHS

Hypoplastic (HI-puh-plas-tik) left heart syndrome (HLHS) is a rare and serious defect in which the structures of the left side of the heart (the left ventricle, the mitral valve, and the aortic valve) are underdeveloped. As a result, blood cannot be adequately pumped throughout the body.

More to Know

Hypoplastic left heart syndrome is present at birth (congenital) and has no known cause. It is usually diagnosed within the first few days of life. Without surgery to repair the heart, HLHS is fatal.

Once diagnosed with HLHS, most babies will undergo a series of three operations beginning shortly after birth and ending at 3 years of age. For some babies, heart transplant is the best option if a donated organ is available.

Keep in Mind

While many babies now survive HLHS, they need to be monitored closely by a cardiologist for the rest of their lives. Many complications can occur with HLHS and sometimes additional heart surgery or even heart transplant may be necessary as children born with HLHS get older.

All A to Z dictionary entries are regularly reviewed by KidsHealth medical experts.